When thing's are going as well as they have been for Instagram, it's only a matter of time before something goes awry. It appears the impressively popular Instagram Android app has an evil twin which contains malware and racks up a users phone bill by texting premium numbers.

Instagram's arrival on Android sent shock waves through the app community as within a week it had amassed over 5 million downloads. The app then went on to be bought by Facebook for $1 billion dollars, not bad for a 13-strong team from San Francisco.

By being placed squarely in the spotlight of popularity however, the app has attracted some unwanted attention. A Russian website masquerading as Instagram's official site cropped up late last week (above) and offered what appeared to be the legitimate Android application to potential users.

On closer inspection, the app is in fact a poor substitute for the real thing and according to security entity Sophos, who tested the doppelgänger, it contains malware that has the ability to spam premium numbers via SMS without the user's knowledge racking up a huge bill, the money of which presumably goes to the apps' creators.

The app in question isn't available from the Google Play store (it's only available as a download for users allowing 'Unknown Sources') and as such, this is still the safest way to download apps to your Android device.

Interestingly enough, inspection of the contents of the .APK reveals an unusual set of JPEG images of the same man with a blank expression. It turns out the image which was taken from a Russian wedding photo is a popular popular viral image on Russian online image boards and forums. The significance of the man is unknown but perhaps he didn't get on well with the creator of the unsavoury app.

Unfortunately, this is not a confined case, with games being a particularly popular target for app developers with criminal intent. Major titles like Angry Birds Space and Madden NFL 12 have also been found to have dangerous clones on the loose.

If you're going to download Instagram - make sure you get it from the Google Play Store.